Chronological, petrologic and geochemical characteristics of Tawenchahanxi granitic diorite porphyry in East Kunlun Mountains and its metallogenic significance

The Tawenchahanxi Fe-polymetallic deposit is another typical skarn type deposit newly discovered in the Qimantag metallogenic belt of East Kunlun Mountains. Using LA-ICP-MS zircon U-Pb isotope dating, the authors obtained the petrogenetic age of the granitic diorite porphyry (236.0±2.3Ma.) which is the main ore-forming rock mass in the mine. The result is in agreement with previous isochron age of 229.9±3.5Ma of the muscovite separated from skarn magnetite ore by the ⁴⁰Ar-³⁹Ar incremental heating method. Petrologic and geochemical data indicates that it is a peraluminous granite and belongs to the I type high K calc-alkaline series, enriched in LREE and HFSE but depleted in HREE and LILE. The rare earth patterns of rocks/chondrite show medium negative Eu anomalies. In addition, the diorite porphyry might have been formed at the collision-post collision stage of Late Paleozoic to Early Mesozoic tectono-magmatic cycle, which was also related to regional large-scale mantle magma underplating and crust-mantle magma mixing.